The present disclosure describes systems and techniques relating to communications between an electric vehicle and a charging station.
A pluggable Electric Vehicle (EV) should be able to communicate charging control and billing information with an Electric Vehicle Supply Equipment (EVSE) device. EVSE typically includes an EV charger, separate electricity usage meter, and associated electronics to manage the charging sessions. The typical EVSE cable that links the EV with the EVSE is known as a J-1772 cable. This cable has various wires in it, and among these wires are a control/sense wire (or wires) used by the EV and EVSE for detection of when the cable is connected to an EV, plus those wires used for charging the EV located batteries.
Over the J-1772 cable will be passed command and control data related to the identification and billing information of the vehicle, possibly maintenance data to be passed to a servicing company (if there is an Internet link to the EVSE), battery charge state, battery health, and other similar data. The microcontroller in the EV signals the EVSE microcontroller to begin the charging. The EVSE, through its links to the utility, its rate/billing database, and its relative ampere flow capacity, will establish a rate of charge, possibly delayed due to utility command, and may fluctuate the charge based on remote commands, billing rate for the electricity used, and user input (e.g., a request for rapid charge).
Once the microcontroller of the EV determines its batteries are fully charged, it notifies the EVSE, and charging is halted. The sense/control leads act as triggers to apply power to the J-1772 cable, thus ensuring a safety margin, and the absence of a sense signal over these leads causes the E\/SE to immediately remove power from the J-1772 cable, again as a means of safety. The charge wires are used for this function and are relatively larger in wire gauge versus the sense leads.